Method of making pressure cartridges



Nov. 12, 1935. G. 1.. TlNKHAM METHOD OF MAKING PRESSURE CARTRIDGES Original Filed Jun '22, 1934 INVENTOR. 51/51 L- NKHAM BY 3m MM ATTORNEYS v Patented Nov.

UNITED STATES PATENT OFFICE METHOD OF MAKING PRE S S URE CARTRIDGES Guy L. Tinkham, McCord Radiator corporation of Maine Original application 731,795. her 8, 1934,

5 Claims.

The weldat the cap or the electrode may be revolved about Also in carrying L5 charge in the shell In the accompan the same purpose.

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tion of a form of apparatus which may be emi played for electric ally welding the cap to the Detroit, Mich., assignor to & Mfg. 00., Detroit, Mich., a

June 22, 1934, Serial No. Divided and this application Decem- Serial No. 756,581

pressure charge has been placed accordance with the method of the shell. 3 in Fig. 1, preferably comprises solid carbon dioxide.

This with carbon tetrachloride. from the reservoir between the shell and the cap while welding the cap to the shell in accordance with my invention. 1e at is in annular form so that the seal orovides is continuous about the cap, as n Fig. 5. The gasket may be of stain- I or other desired metal and is apertured nter so that a portion of the cap wall 8,

ntly described, may be directly expressure charge within the shell. l is preferably formed by pressing the shell wall inwardly as shown. The cap while g tightly pressed into the shell against the et, is welded to the shell at the contacting walls 9 and ii to provide a welded seal between 15 the cap and the shell, which seal effectively prevents leakage of pressure from the cartridge and retains the latter potent until used.

The bottom wall 8 of the cap has its central portion reduced in thickness as at 3 whereby 20 the pin 6 under a pressure of between eleven to fifteen pounds may puncture the cap to release he internal pressure from the cartridge. The thin portion i3 is produced by grinding off the metal to the thinness desired, as for example approximately .018 to an inch. The grinding operation can be localized by having the thin portion at the outer end of a protuberance l4 pressed outwardly from the bottom wall of the cap. In practice the protuberance is drawn to 30 approximately the thickness of the metal of the cap and made straight or flat at the portion to ground. In the particular form of construction shown in the drawing, the protuberance is pressed outwardly from the wall 8 to the side 0p posite the marginal wall 9. Thus the protuberance may be reached for grinding without hindrance by the marginal wall. Also the protuberance may extend into the shell through the gasket and be directly exposed to the pressure 40 charge in the shell. While the puncturing section shown in the drawing is applied to the cap, it is to be understood that it is within the contemplation of my invention to provide the puncturing section in the shell wall, as at the end of 45 the shell opposite the cap, in which event the cartridge would be reversely arranged in the chamber 4.

In securing the cap to the shell, after the pressure charge has been placed in the shell, the cap 50 is pressed into the shell toward the shoulder H. Suiiicient pressure is applied to tightly seat the gasket against the shoulder. While the cap is so held, the marginal wall 9 of the cap is electrically welded completely about the same to the 55 wall portion 1% of the shell beyond the outer edge of the gasket as indicated at l in Figs. 1, 3 and 4. Spot welding s. ich overlaps is employed to provide a continuous welded connection between the cap and the shell to the full circumferential ex- 60 tent thereof as shown in Fig. 4. This effectively secures the cap to the shell and provide a welded seal which prevents leakage of the pressure cm the shell. A form of apparatus for welding the cap to the 65 shell accordance with my invention is shown in Fig. 2. Briefly the apparatus comprises a support for the shell and a holding member I! This member does not fit tightly hin the cap, there being sufficient clearance een the member and the marginal wall of o prevent welding of the cap to the mem ing operation. The support It) shown so that the cap may be tly Cod into the shell to clamp the gasket etween the cap and the shell at the shoulder l l.

The member is in the form of a screw for this purpose and carries a rotatably mounted socketed portion 28 at its inner end to receive an support the closed end of the shell. The mem er I! constitutes one of the electrodes of the weld 5 ing apparatus. The other electrode i9 is in the form of a disc adapted to brought into peripheral contact with the wall portion if) of the shell for electrically welding the cap to the shell.

A pressure device 2i: is employed for holding the 10 disc in contact with the shell. The disc 19 and the cap holder H are rotatable to secure a welding connection between the cap and the shell completely about the same as described. The disc and the cap holder are preferably rotated by 15 power and at such speed as to quickly weld the cap to the shell without an opportunity being afforded for the heat generated in the welding operation to be transferred to the pressure charge for increasing its pressure beyond a safe working 20 pressure. To carry off this heat and thus prevent a noticeable increase of internal pressure in the cartridge during the welding operation, I subject the exterior of the shell and also the electrodes to a suitable coolant. This may comprise a suitable liquid flowed onto the parts from one or more tubes or pipes, one of which is shown at 2| in Fig. 2.

In the welding apparatus shown, the cap holding member I! is rotatably mounted in the frame of the device and is turned by suitably arranged gearing. The socketed member 18 in being rotatably supported by the screw l6 enables the shell I to turn in union with the cap 2 even though the parts are tightly pressed together by the screw. The cap and the shell are made of the same metal and preferably of the same gage. The circuit for the electrodes contains an interrupter (not shown) which provides for the spot welding. The arrangement is such that the spots overlap to provide a continuous weld about the cap, and thus the sealing function of the gasket is not dependent upon to prevent leakage from the cartridge. The gasket is employed to seal the joint while the cap is being welded to the shell. The coolant may be flowed by gravity or by pressure as may be desirable.

The advantages of the invention are that the welded connection between the cap and the shell provides an effective means for securing the cap to the shell and for preventing leakage of pressure from the shell. Thus the cartridge is kept potent until used.

It is to be of course understood that the electrodes are to be suitably insulated from each other and from the machine frame and the parts which support and operate them.

I claim as my invention:

1. The method of securing a closure cap to the shell of a pressure cartridge of the character described, consisting in pressing the cap into closing relation with respect to the shell with a gasket between the cap and the shell to seal the joint between them while welding the cap to the shell, and then welding the cap to the shell to provide a welded seal between the cap and the shell.

2. The method of securing a cup shaped closure cap to the shell of a pressure cartridge of the character described, consisting in forcing the cap into the shell with a gasket between the cap an d the shell to seal the joint between them while welding the cap to the shell, and while holding the cap against the gasket and in tightly clamped relation with respect to the shell, welding the 7 and while holding the cap under pressure against in contact with the shell, subjecting the cap and the shell to an electrical welding current to electrically weld the cap to the shell.

4. The method of securing a closure cap to the shell of a pressure cartridge of the character described, consisting shell, and while holding the cap tightly pressed against the gasket and in contact with the shell, revolving the cartridge and subjecting the same spraying a coolant on tridge to maintain the internal pressure charge in the shell at a safe working pressure.

GUY L. 'I'INKHAM. 

